Electron beam control system for vertical strip color tube



R. D. THOMPSON June 20, 1961 ELECTRON BEAM CONTROL SYSTEM FOR VERTICALSTRIP COLOR TUBE Filed OC'L. 20. 1954 4 Sheets-Sheet 1 June 20, 1961 R.D. THOMPSON ELECTRON BEAM CONTROL SYSTEM FCR VERTICAL STRIP COLOR TUBEFiled Oct. 20, 1954 54M Jef/U INVENTOR. oaf T10/wia# BY fro/Mfr June 20,1961 R. D. THOMPSON ELECTRON BEAM CONTROL SYSTEM FOR VERTICAL STRIPCOLOR TUBE Filed Oct. 20, 1954 4 Sheets-Sheet 5 INVENTOR R065? 0.Z100/#50N June 20, 1961 R. D. THoMPscN 2,989,583

ELECTRON BEAM CONTROL sYsTEM ROR VERTICAL STRIP COLOR TUBE Filed Oct.20, 1954 4 Sheets-Sheet 4 INVENTOR. R065@ 7. ZoMso/v United StatesPatent 4O ELEc'moN BEAM coisrRoL SYSTEM FOR VERTICAL STRIP COLOR TUBERoger D. Thompson, Princeton, NJ., assignor to Radio Corporation ofAmerica, a corporation of Delaware Filed Oct. 20, 1954, Ser. No. 463,380'13 Claims. (Cl. 178' .'4)

This invention relates to color television and more particularly tomethods and arrangements for the reproduction of images in substantiallytheir natural color.

It has been previously proposed to reproduce an image in color bycausing a beam of electrons to repeatedly impinge upon different colorlight producing elements. 'Ihe beam of electrons being sequentiallyintensity modulated with signals representative of each of the differentlight colors as it is deflected over the different color light producingelements. The periods or intervals of beam modulation with a particularsignal, must correspond to particular impinging intervals, i.e., periodsduring which the beam impinges upon a particular color light producingelement. Such a system requires accurate controlling of the electronbeam intensity modulation with respect to beam position, such that theinterval during which a color light producing element of a particularcolor is being excited repeatedly will coincide with the interval duringwhich like color signals modulate the electron beam.

'Ihe presentinvention in its more general form applies to a colortelevision receiver wherein an electron beam repeatedly impinges uponvarious light producing elements on a target electrode, and is a methodand apparatus for applying to the electron beam during particularkintervals, color signals which are representative of colors whichcoincide with the colors produced by the light producing elements onwhich the beam repeatedly impinges. The system Iutilizes certain signalgenerating elements placed on the target electrode, which are sopositioned as to generate a control signal indicative of the position ofthe electron beam with respect to the light producing elements. Thecontrol signal generated by the signal generating elements is not onlyused to maintain the correct relationship between the time intervalduring which the electron beam impinges on a particular lightproducingelement, and the time interval din-ing whichv the electron beam ismodulated by a particular color signal by sequentially switching theappropriate color channels on to the electron beam control means but thecontrol signal is also employed to control the sequence rate which issubject to change if non-linear Vdeiection s experienced.

An object of this invention is to provide an improved color televisionimage reproducing system.

Another object of this invention is to provide an improved electron beamcontrolling system by means of which an electron beam may be caused toexcite a series of light producing Velements according to the receptionof video signals representing the colors reproduced respectively by saidelements.

A further object of the invention is to provide a color television imagereproducing system in Which'a multicolor ikinescope is used, having avertically arranged striplike light-producing element target in which isincorporated facilities for generating control signals which may beutilized to control the intervals of intensity modulation of theelectron beam with respect to the intervals during which different lightcolors are produced by the kinescope.

Other and incidential objects of this Ainvention will be apparent tothose skilled in the art from reading the -following specification andon inspection of the accompanying drawings in which:

FIGURE 1l shows a block diagrammatic representation of one Aform of theinvention.

2,989,583 PatentedV June 20, 1961 FIGURES 2A and 2B show views of a formof a target electrode to be used in the kinescope of a system of theinvention shown in FIGURE 1.

FIGURES 3a, Sband 3c show various curves and diagrammaticrepresentations to be used in the explanation of the invention.

FIGURE 4 shows a block diagrammatic representation of another form ofthe invention.

FIGURE 5 shows one form of a variable phase shifter which may be used inthe diagrammatic representation of FIGURE 1.

FIGURE 6 shows one form of gate circuit which may be used in thediagrammatic representation of FIGURES 1 and 4.

FIGURE 7 shows one form of a photocell voltage control circuit which maybe used in the diagrammatic representations of FIGURES 1 and 4.

Referring now to FIGURE 1 there is shown a television receiver 10 whichis utilized for receiving a television signal and forming therefrom 3image component color signals. The color signals being a green signal, ablue signal, and a red signal. A television receiver for deriving suchcolor signals from a received color television signal is shown anddescribed in Radio Television News May 1954, in an article entitledFundamentals of Color Television by Milton S. Kiver. 'I'he color signalsgreen, blue and red are applied respectively to gate circuits 12, 14 and16. A further gate circuit 18 is provided to gate a substantiallyunvarying voltage from a voltage source 20. The gated color signals fromthe gate circuits 12, 14, 16 and the gated unvarying voltagev from thegate circuit 18 are combined and applied to a cathode 21 of an imagereproducing tube 22. The control or gating of the circuits 12, 14, 16and 18 is effected by gating signals from variable phase shiftercircuits 24, 26, 28 and 30. A control signal is generated within theimage reproducing tube 22. The detailed manner which the control signalis generated will be later explained; however, generally, the controlsignal results from electron beam energy exciting signal generatingelements within the image lreproducing tube 22. The light controlsignals emitted from the signal generating elements are` selected fromotherlight signals by a wave length selec-y tive light lter 37, andconverted into electrical control signals at the photoelectric cell 36which serves as 4a sensing means.

.It is to be understood that in other forms of the invention othermethods than light control signal generating elements may be used, forexample, electron emissive elements, or electron conductive elements.

The control signal is separated into a low pass control signal by a lowpass filter 34, and a band pass control signal by a bandpass iilter 38.The bandpass control signal is applied to the variable phase Shifters24, 26, 28 and 30 to be shifted in phase yand formed into gating signalsto control the operating and closing of the gate circuits 12, 14, 16 and1S. The low pass control signal is amplilied by a D.C. amplifier 32 andapplied to the variable phase Shifters 24, 26, 28 and 30 to vary thephase shift effected by the respective phase Shifters. The low passcontrol signal thus acts as a phase shift control signal to vary thedegree of phase shift of the gating signals.

The low pass control signal, passing through the low pass iilter 34 isalso utilized as a servo control lfor the voltage supply to thephotoelectric cell 36 to provide control of phototube gain. The signalis fed to a peak detector 40 and then amplified in a D.C. amplifier 42,after y which it is applied to a phototube voltage control circuit 44 tovary the voltage applied at the photoelectric cell from a voltage source46 in accordance with the amplitude of -the peak amplitude of the lowpass control signal. Since this rectification is of the peak type, re-

will be proportional to the phototube output produced during the initialportion of each horizontal scan, in which sampling has not yet begun.The signal so produced -thus provides a reference signal to set thephotocell voltage.

The image reproducing tube 22 is also provided with deection coils 23 tobe utilized to cause an electron beam in tube 22 to scan a rasterpattern.

Before explaining the operation of the system shown i n FIGURE l thetarget electrode utilized in the image reproducing tube 22 which isshown in FIGURES 2A and 2B will be considered.

The target electrode as shown in FIGURES 2A and 2B consists of afoundation plate 50 having strip-like color light producing elements R,B, and G positioned thereon. As taught by Leverenz in United StatesPatent No. 2,310,863 when the light producing phosphor elements whichmake up the different groups are to emit blue, green and red light,respectively, the materials of which the elements are composed maycomprise: silver activatedv zinc sulfide and zirconium silicate for theblue elements B, alphawillemite activated with manganese or zinc cadmiumsulfide activated with silver for the green elements G,chromium-activated aluminum berylliiate or zinc cadmium sulfideactivated by silver for the red elements R.

Every Ifourth element position in the pattern of the image screen isopaque and unoccupied by light producing material in the plane of thelight producing elements R,`B, and G. Positioned upon the lightproducing elementsy R, B, and G is. an electron-transparentlight-refleeting layer 52 which may be composed of aluminum. A series ofultra violet light emitting phosphor coating elementsl 54 are thenpositioned in registry with one side of the strip-like area which isunoccupied by light producing material. The ultra violet light emittingelements may be composed of calcium magnesium silicate, .zincY oxide orother fast phosphor materials.

In regard to the operation of the system shown in FIGURE 1 it is desiredto control the gate circuits 12, 14, 16 and 18 by the application ofgating signals in such av manner that the electron beam in the imagereproducing tube 22 is sequentially modulated with the followingdifferent signals: a red signal, a blue signal, a green signal and -asubstantially unvarying signal. The intervals during which the electronbeam is modulated with these different signals must coincide with theintervals` during which the electron beam impinges upon the diiferentstrip-like color light producing elements on the image screen within thereproducing tube 22. During the time when the electron beam impingesupon the signal generating elements, or in this case the ultra violetlight emitting elements of thetarget electrode which in this form of theinvention are utilized as the signal generating elements, ultra violetlight will be emitted. The ultra violet light control signals are sensedthrough the light filter 37 by the photoelectric cell 36 positioned in awindow of the image reproducing tube 22. The control signals sensed bythe photoelectric cell 36 will be filtered by the band pass filter 38and then applied to the variable phase shift circuits 24, 26, 28 and 30,wherein there are formed four gating signals each of which is shifted`substantially 90 from the other. The 90 phase shifted gating signalswhen applied to the gate circuits 12, 14, 16 and 18wwi1l thereforesequentially allow the passage of the substantially unvarying signalthrough the gate circuit 18, the green signal through the gate circuit12, the blue signal through the gate circuit 14 and the red signalthrough the gate circuit 16, to the cathode 21 of the image reproducingtube 22. As these signals are sequentially applied to the cathode 21,the electron beam in the tube 22 will be intensity modulated accordingto the intensity of the gated signals. The low pass controlsignalpassingthrough the low pass lter 3 8 is utilized to sensitively control theamount of phase shift elected by the variable phase shift circuits 24,26, 28 and 30. The low pass control signal is separated in the low passfilter 34 and amplified in the D.C. amplifier 32 and results in a phaseshift control signal. The phase shift control signal is utilized as acorrection signal to vary the degree of phase shift effected by thevariable phase shifter circuits 2,4, 26, 28 and 30, and therebyeffectively assures correct beam modulation with respect to the electronbeam position.

The manner in which the phase shift control signal is utilized will beexplained with reference to FIGURES 3A, 3B land 3C. There is shown inFIGURES 3A, 3B and 3C an enlarged portionof the ultra violet lightemitting element 54 and the adjacent opaque area 55. Areas 60, 62, 66,68, 74 and 76 represent various areas on which an electron beam withinthe image reproducing tube may impinge upon the target electrode. Thoughan electron beam of a square cross section is shown, such is the caseonly for purposes of illustration, and it may be seen, that moreirregular electron beams will give satisfactory performance.

Consider iirst- FIGURE 3A and assume that the electron beam has beenreceiving a substantially unvarying potential for atime since it was ina position as to impinge on the dashed line enclosed area 60 where itcarne initially in contact with the ultra violet light emitting element54. Assume further that the electron beam became turned off, so tospeak, i.e., dropped to a low intensity level upon reaching a positionas shown by a solid line enclosed area 62. There is shown a curve 64which. indicates the control signal generated when the electron beam isturned on at a position shown by area 6,0 and turnedoff at a. positionshown by area 62. The curve 6,4v will be seen to be representative of acontrol signal of continually increasing magnitude as the electron beam.is moved on to the element 54 causing a greater number of the electronswithin the electron beam to impinge upon the ultra violet light emittingphosphor element 54.

Referring now to FIGURE 3B there is shown a control signal which wouldbe generated if the electron beam were keyed on to a substantiallyunvarying intensity when inV position as shown by dashed line enclosed.area 66, and werekeyed. oif when in a position substantially as shownbysolid line enclosed* area 68. It may be seen that the control signal asshown in curve 70 will be generated having increased direct currentcomponent over theL control signal shownv by the curve 64. In the caseas shown in FIGURE 3B it will be seen that the electron beam has beenkeyed on at a time later than t-he case shown in FIGURE 3A-or phase timedelayed.

Referring now to FIGURE 3C there is'shown a control signal incurve 72which is representative of the signal which wouldbe generated if theelectron beam were keyed onat the position asshown by the dashed lineenclosed area 74 and keyed off at the position shown by the solid lineenclosed area v76. In considering the curves 64, 70, and 72, it will beseen that as the gating or keying signal is varied inphase with respectto the scanning of the signal generating elements the generated signalwill vary both in'magnitude and peak intensity.

A consideration of the FIGURES 3A, 3B, and 3C indicatesthat thefrequency ofthe control signal and the amplitude ofthe control signalwill be indicative, of the position of the electron beam. The bandpasscontrol signalthus becomes a signalwhich in frequency isindicative ofthe number ofsignal generating elements scanned by the electron beamduring a particular period. The bandpass control signalvmay, thus beutilized to generate the gating signals for switching the Kapplicationof the different color signals andthe unvarying voltage to the cathode20 of image reproducing vtube- 2.2.1 A'l similar Switching. mengementis..shQwnand-- descnibedgin United S States Patent No. 2,545,325, issued toP. K. weimer, March 13, 1951.

The amplitude and the direct current component .of the control signalsshown in curves 64, 70 and 72 may be seen to vary as the interval duringwhich the electron beam is keyed to a substantially unvarying voltage inrelation to the deflected position of the electron beam on the targetelectrode. If the keying is properly timed with respect to the scanningof the signal generating element 54, the control signal will be of anamplitude as shown in curve 64. If the keying to substantially unvaryingVoltage is delayed with respect to the signal generating element 54, asshown by FIGURE 3B, the control signal will be of increased amplitudeand have a greater direct current leomponent las shown in curve 70, thanit had in curve 54. If the keying of fthe electron beam intensity to asubstantially unvarying value is premature with respect to the signalgenerating element `54, as shown in FIGURE 3C, then a control signal oflesser amplitude and having a smaller `direct current component will begenerated as shown by curve 72. It may therefore be seen that the lowpass control signal which varies as the direct current component of lchecontrol signal is a sensitive indication of the timing relationship ofthe electron beam intensity modulation with respect to the position ofthe electron beam. The low pass control signal may therefore be utilizedlas a phase shift control signal to vary the degree of phase shifteffected by the variable phase Shifters 24, 26, 28 and 30. The controlsignal amplitude or condition which exists as shown in FIG- URE 3A maybe set as an equilibrium condition, and if the control signal generatedincreases in magnitude 'and direct current component the phase of thegating signals will require to be phase advanced, whereas if the controlsignal generated decreases in magnitude and direct current component, itwill be indicated that the phase of the gating signals should be phasedelayed.

Referring now to FIGURE 4 there is shown another form of the inventionillustrated by a system having an image reproducing tube 22 with atarget electrode substantially as shown in FIGURES 2A and 2B. Componentsof the systems shown in FIGURE 4 which are similar to components inFIGURE l are similarly numbered.

The television receiver is utilized to generate a green signal, a bluesignal, and a red signal. The various color component signals areapplied sequentially along with `a substantially unvarying signal to thecathode 21 of the image reproducing tube 22 to sequentially modulate theelectron beam as described with reference to FIGURE l. The gate circuits12, 14, 16 and 18 are controlled by phase Shifters 82, 84, 86 and 88which are not variable. 'Il-he phase Shifters 82, 84, 86 and 88 act uponsignals received from -an oscillator 90 to produce diierent gatingsignals each being substantially 90 displaced from the other to beutilized to control the gate circuits 12, 14, 16 and 18. The controlsignal sensed as previously described by the photoelectric device =36through the lter 37 is passed through the low pass ampliiier 34 andthence applied to auxiliary `deflection plates 92 positionedl within theimage reproducing tube 22.

In the system as shown in FIGURE 4 the variation to correct fordeviation in the timing between the intervals during which the electronbeam is intensity modulated With the different component color signals,and the i11- tervals during which the electron beam i-mpinges upon thediiferent light producing strip-like elements of the image screen ismade by Varying the time of occurrence of the impinging intervals byutilizing the auxiliary deecting plates 92 to alter the beam position.That is t0 say, 'if the electron beam is being modulated by, forexample, a green signal but is still impinging upon `a blue colorproducing element, the auxiliary deflecting means 92 will tend todeflect the electron beam as it scans further to cause'the period duringwhich the beam is intensity modulated with a green component signal tocoinbetween the interval of modulation, and the interval ofV f 6 cidewith the period during which the electron beam impinges upon the ygreelight producing element.

It may therefore be seen by comparing FIGURES 1 and 4 that in diierentforms of the invention a correction signal may be formed to vary theposition of the electron beam of the intensity modulation intervals ofthe electron beam, to maintain the correct relationship beamimpingement.

FIGURE 5 shows a form of a variable phase shifter which may be used asthe variable phase shifter circuits 24, 26, 28 and 30 of VFIGURE 1.Terminal 100 is provided for receiving a direct current voltage whichvaries as the amount of phase shift desired. 'I'he direct currentyvoltage applied vat terminal 100 will pass through inductive elements102 and 104. The inductive elements 102 and 104 are inductively coupledto inductance elements 106 and 108. The inductance elements 106 and 108form part of a delay line 110 which also includes capacitors 112, 114and 116. An alternating current signal applied at terminal 118 will bephase delayed by a prei determined amount on passing through the phasedelay line 110. The application of a direct current voltage to terminalwill vary the inductance reactance of the induotance elements 106 and108 and will therefore vary the degree of phase shift affected by thedelay line 110. It may therefore be seen that if the low pass controlsignal is applied to the terminal 100, and a bandpass control signal isapplied to the alternating current terminal 118, the low pass controlsignal will vary the phase delay aifected in the bandpass signal by thedelay line according to the amplitude of the low pass control signal.

FIGURE 6 shows a form of a gating circuit which may be used as thegating circuits 12, 14, 16 and 18. A gating signal is applied to theterminal 122. The signal to be gated is applied at the terminal 124.Both terminals 122 and 124 are connected to current control grids of anelectron discharge device 126. The current through the electrondischarge device 126 will therefore be controlled by the potentialapplied at the terminal 122 and 124. The electron discharge device 126is so biased that until the gating signal applied at terminal 122reaches a predetermined amplitude, no signal will pass through theelectnon discharge device 126 and no alternating signal will appear atthe output terminal 128. Upon the occurrence of a gating signal above apredetermined magnitude the electron discharge device 126 Will becomeconducting, however, the current through the device will be modulated inaccordance with the signal applied at the terminal 124. In this manner agated color signal may be caused to periodically appear at the outputterminal 128 upon the occurrence of a gating signal applied at theterminal 122 of a particular amplitude.

In the event that the direct current signal from the peak detector 40 ofFIGURE l decreases in amplitude the decrease will be sensed by theconnection from the peak detector 40, and cause the photocell 36 toreceive a voltage of increased magnitude thereby regulating theamplitude of the control signal to compensate for power fluctuations.

FIGURE 7 shows a form of photocell voltage control circuit 44 which maybe used in the system of FIGURES l and 4. Terminal 130 is adapted to beconnected to a source of negative potential. The negative potential iscoupled through cathodes in electron discharge devices 134 and 138. Theelectron discharge device 134 has a control grid connected through abattery 136 to a plate of the elect-ron discharge device 138. Theelectron discharge device 138 acts as a direct current amplifier andthereby applies a potential to the control grid of the electrondischarge device 134. As the cathode potential at the electron dischargedevices 134 and 138 varies, the output voltage appearing at terminal 140will also vary because Ythe potential is dependent upon the voltageapplied to the control grid of the tube 138. It may there,

fore ,be seen that the output potential appearing at terminal 140 willvary vas the input signal applied at the electron discharge device 138through input terminal 142 and the signal from the .peak detector 40 ofFIGURE 1 may be applied at the input terminal 142 to vary the phototubevoltage control circuit, and thereby Vary the voltage supplied at thephotoelectric cell 36.

lIn still another form of this invention a well regulated Voltage supplymay be applied directly to thephotocell 36 .without employing thephotocell voltage control circuit including the photocell voltagecontrol circuit 44, the D.C. amplifier 42, and the peak detector 40.

It may therefore be seen that the invention provides an improved systemfor reproducing color images, utilizing asingle electron beam withapparatus to maintain the registry of the electron beam correct withrespect to the image reproducing screen.

What is claimed is:

l. An electron beam control system comprising a target electrode havinga plurality of light producing elements and a plurality of signalgenerating elements, said light producing elements being responsive toemit light energy when excited by electron beam energy, said signalgenerating elements being responsive to generate a control signalincluding low frequency components when excited by electron beamrenergy,means for forming an electron scanning beam for exciting said elements,controlled modulating means for intensity modulating said electron beamwith different values during different time intervals of modulationincluding a reference value at times when said beam impinges upon saidsignal generating elements, each lof said time intervals of modulationsubstantially coinciding with a particular impinging time intervalduring which said electron beam excites certain of said elements,frequency discriminatory sensing means for sensing the amplitude of thelow frequency components of said control signal, varying means connectedto receive said control signal, said varying means for varying said timeinterval of modulation with respect to said particular impinginginterval in accordance with the amplitude of said control signal.

2. A device according to claim l wherein said varying means comprisesdellecting means for deilecting said electron beam commensurate withsaid control signal to thereby vary the time of occurrence of saidimpinging interval.

3. A device according to claim l wherein said varying means comprisesswitching means connected to said modulating means, said switching meansbeing such as to vary the time of occurrence of said interval ofmodulation commensurate with said control signal.

4. A color television image reproducing system comprising in combinationa target electrode having a plurality of light producing elements. and aplurality of signal generating elements, said light producing elementsbeing responsive to emit light energy when excited by electron beamenergy, said signal generating elements being responsive to generate acontrol signal when excited by electron beam energy, means for formingan electron scanning beam for exciting said elements, gating meansadapted to be connected to sources of a plurality of different signalsincluding a source of unvarying signal, beam intensity control meansconnected ,to said gating means, said gating means being operative tomodulate said beam with said unvarying signal at times related to theimpingement of said beam upon said signal generating elements, sensingmeans for sensing said control signal ygenerated by said signalgenerating elements, variable phase shift means connected to saidsensing means for generating a phase shifted gating signal for each ofsaid different signals, means for applying said gating signals to saidgating means such as to control the application of said differentsignals to said beam intensity control means for modulating saidelectron beam sequentially with said different signals, means forisolating the low frequency components of said control signal to form aphase control signal, and means for applying said phase control signalto said variable phaseshift means for varying the phase shift effectedby said variable phase shift means as a function of the amplitudeA ofsaid low frequency components. Y

5. A color television image reproducing system comprising in combinationa target electrode having a plurality of light producing strip-likeelements., and a plurality of signal generating strip-like elements,saidlight producing strip-like elements being responsive to emit lightenergy when excited by electron beam energy, said signal generatingstrip-like elements being responsive to generate a control signal whenexcited by electron beam energy, means for forming an electron scanningbeam for exciting said strip-like elements, gating means adapted to beconnected to sources of plurality of different signals including anunvarying reference signal, beam intensity control means connected tosaid gating means, sensing means for sensing said control signalgenerated by said signal generating strip-like elements, variable phaseshift means connected to said sensing means for generating a phaseshifted -gating signal for `each of said different signals, means forapplying said gating signals to said gating means such as to control theapplication of said different signals to said beam intensity controlmeans for modulating said electron beam sequentially with said differentsignals and with said reference signal when said beam impinges upon asignal generating element, means for isolating certain frequencycomponents of said control signal to form a phase control signalindicative of the amplitude of said certain frequency components, meansfor applying said phase control signal to said variable phase shiftmeans for varyu'ng the phase shift effected by said variable phase shiftmeans as a function of the amplitude of said certain frequencycomponents, and means for receiving certain frequency components of saidcontrol signal for controlling variations in said sensing means. y

6. A color television image vreproducing system comprising incombination a target electrode having a plurality of light producingelements and a plurality of signal generating elements, said lightproducing elements being responsive to emit light energy when excited byelectron beam energy, said signal generating elements being responsiveto generate a control signal including low frequency components whenexcited by electron beam energy, means for forming an electron scanningbeam, electron beam dellection means for deflecting said electronscanning beam in a scanning pattern to excite said elements, gatingmeans adapted to beconnected to a plurality of sources of differentsignals including an unvarying reference signal, beam intensity controlmeans connected to said gating means, sensing means for sensing saidcontrol signal generated by said signal generating elements, phase shiftmeans connected to said sensing means for generating from said controlsignal, a phase shifted gating signal for each of said differentsignals, means for applying said phase shifted gating signals to saidgating means such as to control the application of said differentsignals to said beam intensity control means for modulating saidelectron beam sequentially with said different signals and with saidreference signal when said beam impinges upon a signal generatingelement, means for isolating said low frequency `components of saidcontrol signal to form a deflection correction signal, auxiliarydeilecting means for imparting additional deflection to said electronbeam, and means for applying said deflection correction signal to saidauxiliary deflection means to control deflection of said beam as afunction of the amplitude of said low frequency components of saidcontrol signal.

7. A color television image reproducing system comprising in combinationa target electrode having aplurality'of light` producing strip-likeelements and a plurality of signal ygenerating strip-like elements, saidlight aesasa elements being responsive to emit light energylI whenexcited by electron beam energy, said signal generating strip-likeelements being responsive to generate a control signal including lowfrequency components when excitedV by electron beam energy, means forforming an electron' scanning beam, electron beam deflection meansfor'ldeiiecting said electron scanning beam in a scanning pattern toexcite said elements, gating means adapted to be connected to aplurality of sources of diiferent signals, b'eam intensity control meansconnected to said `gating means, sensing means for sensing said controlsignal generatedby said signal generating strip-like elements, phaseshift means connected to said sensing means for generating from saidcontrol signal a phase shifted keying signal for each of said differentsignals, means for applying said gating signals to said gating meanssuch as to control the application of said ldierent signals to said beamintensity control means for modulating said electron beam vsequentiallywith said different signals and with an unvarying Areference signal attimes related to the times of beam impingement upon said signalgenerating elements, means' for isolating saidlow frequency componentsof said control signal'to'form a deilection correction signal, auxiliarydeecting means 4for imparting additional deflection to said electronbeam, means for applying said deflection correctionsignal totsaidauxiliary deilection means, and means 'adapted to receiye saidlowfrequency components forfcontrolling the voltagesupplied to said sensingmeans.

"8. Iny a color television system embodying a color kinescope having atarget formed of groups of strip-like elements, each. .group ofstrip-like elements for producing light ivithinaparticular range of Wavelengths whenl excited byelectron beam energy, at least oneof said groupsofl'strip-like elements' forV producing a control signal including lowfrequency components, means for generating an j electronubeam ,forexciting said Vstrip-like elements, beam modulating means for modulatingsaid electron beam alternately with different signals and for modulatingsaid beam to a reference value at times related to its impingement uponsaid control signal producing elements, means for controlling said beammodulation means, means for sensing said control signal, means forselecting said low frequency components of said control signal to form acorrection signal which varies as a function of the amplitude of saidlow frequency components, means for coupling said correction signal tosaid means for controlling said beam modulation means such as to causesaid electron beam to be modulated with a signal representative of lightwithin a particular range of wave lengths at a predetermined time.

9. A color television system embodying a color kinescope having a screenformed of groups of strip-like elements, each group of strip-likeelements for producing light within a particular range of wave lengthswhen excited by electron beam energy, at least one group of strip-likeelements for producing a control signal including low frequencycomponents when excited by an electron beam, means for generating anelectron beam for exciting said strip-like elements, beam modulatingmeans for modulating said electron bearn alternately with diierentsignals and for modulating said beam to a reference value at timesrelated to its impingement upon said control signal producing elements,means for sensing said control signal, feedback means for maintainingthe sensitivity of said sensing means substantially constant, means forselecting said low frequency components of said control signal to form acorrection signal, auxiliary beam deflection means, means for couplingsaid correction signals to said auxiliary beam dellection means forcontrolling said beam deflection such that to cause said electron beamto be modulated with a signal representative of light within aparticular range of wave lengths at a predetermined time.

l0. A color television image reproducing system coml prising incombination a target electrode having a plurality of light producingelements, and a plurality of sigl of gating circuits, each of saidgating circuits being connal generating elements,

being responsive to generate a control signal including beam energy,means for forming an electron scanning beam, means for deilecting saidelectron scanning beam in such a manner as to excite said elements, Aaplurality nected to a source of a dilerent signal, beam intensitycontrol means connected to said gating circuits, sensing means forsensing said Vcontrol signal generated by said signal generatingelements, feedback means for maintaining the sensitivity of said sensingmeans substantially con-" stant, variable phase shift means connected tosaid sensing means for generating a phase shifted gating signal for eachof said different signals, means for applying each of said gatingsignals to one of said gating circuits such as to control theapplication of said different signals to said beam intensity controlmeans for modulating said'electron beam sequentially With said differentsignals and for modulating said beam to a reference value at timesrelated to its impingement upon said control signal producing elements,means for isolating said low frequency components of said control signalto form a phase control signal, and means for applying said phasecontrol signal to said variable phase shift means for varying the phaseshift effected by said variable phase shift means.

beam energy, means for forming an elect-ron scanning beam, electron beamdeilection means for deflecting said electron scanning beam in ascanning pattern to excite said elements, a plurality of gatingcircuits, means for connecting each of said gating circuits to a sourceof a diierent signal, beam intensity control means connected to each ofsaid `gating circuits, sensing means for sensing said control signalgenerated by said signal generating elements, feedback means formaintaining the sensitivity of said sensing means substantiallyconstant, phase shift means connected to said sensing means forgenerating from said control signal a phase shifted gating signal foreach of said different signals, means for applying said phase shiftedgating signals to said gating means such as to control the applicationof said different signals to said beam intensity control means formodulating said electron beam sequentially with said different signalsand for modulating said beam to a reference value at times related toits impingement upon said control signal producing elements, means forisolating said low frequency components of. said control signal to forma deection correction signal, auxiliary deflecting means for impartingadditional deflection to said electron beam, and means for applying saiddeflection correction signal to said auxiliary deflection means.

l2. A color television image reproducing system comprising incombination a target electrode having a multiplicity of groups of lightemissive elements, said light emissive elements each being constitutedessentially of a phosphor material capable of emitting light of a colorindividual to that element, said light emissive elements being sopositioned as to leave certain areas on said target electrode void ofphosphor material, a plurality of discrete phosphor coatings disposed onsaid target electrode within said certain areas, said discrete phosphorcoatings being responsive to generate a control signal including lowfrequency components when excited by electron beam er1- ergy, means forforming an electron scanning beam, means for deflecting said electronscanning beam in such a manner as to excite said elements, a pluralityof gating cirsaid light producing` elements being responsive to emitlight energy when excited by' electron beam energy, said signalgenerating elementscuits, each of said gating circuits being connected,toa

source o fga different signal, beamintensity control means conneted'tosaid` gating circuits, sensing means for sensing ,saidY control 4signalgenerated by said discrete phosphor4 coatings, feedbackv means formaintaining the sensitivity ofsaid sensing means substantially constant,variable phase shift means connected to said sensing means forgenerating a phaseshifted gating signal for each of said differentsignals, meansfor applying each of said gating signals to one of saidgating circuits such as to control the application of said differentsignals `to said beam intensity control means for modulating saidelectron beam sequentially with said different signalsand for modulatingsaid beam to avreference value at times related to its impingement uponsaid control `signal producing elements, means for isolating said lowfrequency components ofsaid con-trol signal to form a phase controlsignal whose amplitude varies as a function of the amplitude of said lowfrequency components, and means for applying said phase control signalto said variable phase shift means for varying the phase shift eifectedby saidvariable phase shift means.

13. A color television image reproducing system comprising incombination a target electrode having a plurality of light-producingstrip-like elements, and a plurality of signal-generating strip-likeelements, said lightproducing strip-like elements being responsive toemit light energy when excited by electron beam energy, said signalgenerating strip-like elements being responsive to generate a controlsignal including high and low frequency components when excited byelectron beam energy, means for forming lan electron scanning beam for`exciting said strip-like elements, gating means adapted to be connectedto` a plurality of sources of diicrent signalsincluding an unvaryingreference signal, beam intensity control means connected to' said gatingmeans, sensing means for sensing said control. signal generated by,saidV signal generating` strip-like elements, variable phase, shiftmeans connectedj to said sensingmeans for generatingfromfthe-.high,fre-l quency component of' said control signal a phaseAshifted` keyingsignalfor eachof said different signals, means for,l

applying said, gating signals to said gating means suchV as,

tocontrol theV application of said different signals to said.

beam intensity control means for modulating said electron beamsequentially with said different signals and with saidl unvaryingreference signal at the `times of beamimpingef ment upon said signalgenerating elements, means .connected to said sensing means forgenerating a phase control signal from the low frequency component ofsaid control signal, means for applying said phase control signal tosaid variable phase shift means for varying the phase shift effected bysaid variable phase shift means as a function ofthe amplitude of lthehigh frequency component of said ycontrol signal, and feedback meansconnected to said sensing means and responsive to the low frequencycomponent of ysaid control signal for controlling variations in saidsensing means.

ReferencesCited in the le of this patent.v

UNITED STATES PATENTS 2,633,547 Law Mar. 31,1953 2,635,141 Bedford Apr.14, 1953 2,648,722 Bradley Aug. 1l, 1953 2,664,520 Wiens Dec. 29, 19532,689,269 Bradley Sept.,14, 1954 2,706,216 Lesti Apr. 12, 1955v2,752,418 Clapp June 26, 1956 2,771,503 Schwartz NOV. 20, 1956 2,837,687Thompson et al June 3, 1958 FOREIGN PATENTS 616,012 Great BritainV Jan.14, 1949-

